Spatial and Temporal Trends and the Role of Land Use/Cover on Water Quality and Hydrology in the Fish River Watershed
Type of Degreethesis
DepartmentForestry and Wildlife Sciences
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This study focuses on exploring linkages between land use/cover (LULC) and water quality/quantity at both spatial and temporal scales in the Fish River watershed. The Fish River, in coastal Alabama, is of critical importance to the health of Weeks Bay, a designated Outstanding National Resource Water. The study takes place across ten subwatersheds within the Fish River’s watershed boundaries. Dominant LULCs in the watershed include row-crop agriculture and medium density residential areas. Significant urbanization has occurred across all subwatersheds between 1995 and 2008. Grab samples and stormflow ISCO automated samples were taken and processed to determine concentrations of ammonium + ammonia (NH4+NH3 -N), Nitrate (NO3--N), Total Phosphorus (TP) and Total Suspended Sediment (TSS). Discharge rates were established at each site in order to better quantify subwatershed flows. Spatial comparisons between subwatersheds were linked to water quality and flow trends over time. Data from previous studies in the mid-1990s were compared with this study’s collected data to determine changes in nutrient and sediment levels over time. Only 2 sites showed significant changes in hydrology between the two study periods. Sites with large increases in urbanized land uses had substantially higher TSS concentrations. Nitrate levels between study periods showed a general decrease, while TP concentrations and loads increased significantly between the two time periods. A shift in the nitrogen-phosphorus balance in the Fish River and its tributaries may result in eutrophication of Weeks Bay. The introduction of different crops along with rapidly increased population growth and urbanization are causing substantial changes in the water quality balance within the Fish River and ultimately Weeks Bay.